Spinal disc herniation

Spinal disc herniation describes a tear in the outer, fibrous ring of an intervertebral disc allowing the soft, central portion, called the nucleus pulposus to bulge out beyond the damaged outer rings. Disc herniation is usually due to age-related degeneration of the anulus fibrosus, although trauma, lifting injuries, and straining have been implicated. Tears are almost always posterolateral because of the posterior longitudinal ligament in the spinal canal. If the herniated disc is in the lumbar region the patient may also experience sciatica due to irritation of one of the nerve roots of the sciatic nerve.